cious, and well insulated conductor, produce a sufficient current to work a telegraph from London to Liverpool, Mr. Cooke very positively asserts, "that it will never produce an electric current appreciable by the most delicate test." May I ask by what means he has ascertained this? For from certain results we have seen, we think him rather rash in this opinion; for although Mr. Bain and myself are quite alive to the loss of power in long distances, we endeavour to obviate the evil by good insulation, and by using conducting wires of sufficient capacity. This last remedy of ours, Mr. Cooke appears to have some faith in, for he now recommends them to beth of an inch in diameter, instead of th as heretofore used by him.

As I conceive it bad taste to occupy your pages with a commercial dispute between the proprietors of two telegraphs, now in the market, to the exclusion of much more interesting matter, I shall only remind Mr. Cooke that, he would long since have had an opportunity, (upon upwards of eighty miles of telegraph,) of either verifying his judgment, or showing his want of it, had we not been obstructed (NOT DEFEATED), by most unjustifiable means, well-known to Mr. Cooke, but which I believe him too much of a gentleman to have been a party to. In the mean time, I may state, that we are ready and willing to undertake any length of telegraph at one half the sum per mile DEMANDED by himself: and to keep it in perfect order for the same sum as he would be satisfied with for the same purpose for his. I am, Sir, your obedient servant, THOMAS WRIGHT. Thistle Grove, 10th August, 1843.

WIRE GAUGES.

Sir,-Much has been recently said in your pages about Wire-gauges. Would it not be desirable to know the difference in the lengths of a given weight, say 1 lb. of the different numbers? Distinguishing iron, and other metals. Take any No. of iron wire, say 18, what is the length of 1 lb., and what is the No. of the wire that will be per lb. only half the length, or the No. that will be per lb. double the length? Will wire (iron) of the same weight, but double the length, be only half the strength? If not in that proportion, what is the proportion?

I am, Sir, your constant reader, F. A.

SHIPS' PUMPS.

Sir, I think that ridicule is a bad return for endeavours to be useful, for even when they lead to no good result, the motive

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should be respected. I am led to this observation, by a letter from N. N. L., in your last Number (1044) in reference to the suggestion of Mr. Halse respecting ships' pumps, which has already drawn a letter from one of your correspondents at Liverpool, as well as one from myself. In the case of N. N. L., he evidently thinks that the letter of Mr. Halse, if good for nothing itself, has been the means of eliciting an undoubted improvement," viz. his own proposal: therefore, he ought not to have indulged in sarcasm upon the subject. But if N. N. L. will reflect a little, he will see that his own modification of the ship's syphon is just as inapplicable as the one he condemns so unsparingly. In the first place, the water from ships' pumps is now discharged at the lowest point possible for its escape from the ship; in a line-of-battle ship it runs from the lower deck; in a frigate, or an Indiaman, from the main, or gun deck. Besides, it would be impossible to apply a syphon as mentioned; "the discharging mouth could not be kept below the level of the liquid to be removed," in consequence of the rolling and Be it remembered pitching of the vessel. that ships' pumps are generally brought into requisition by bad weather and a high sea; but if N. N. L.'s plan were practicable, one syphon with a regulating tap, as may be seen by a distiller's wagon, would be quite sufficient. T. W.

I am, Sir, yours truly, 12th August, 1840.

LAW OF PATENTS.-RIGHT OF INSPECTION. ROLLS COURT.-12TH August.

Clarks v. Kenricks.

The plaintiffs in this case are Messrs. Thomas and Charles Clark, of Wolverhampton, the inventors of the well-known and most useful process of enamelling hollow ware, for which they obtained letters patent, on the 2nd of May, 1839. In certain proceedings pending between them and the defendants, for an alleged piracy of their invention, they had obtained an order for permitting an inspection of the defendants' works; but, on the inspectors appointed visiting the premises and seeing all that they could see, they asked the defendants to explain the process they followed, and the materials they made use of. The defendants, acting on the advice of their solicitor, who was present, refused to answer any question, or to permit any samples to be taken, or tests to be tried. Mr. ROTCH now applied to the Master of the Rolls, by special leave, in his private room, for an amended order to compel the defendants to allow the inspectors to examine, test, take samples, &c. The learned counsel argued, that to permit the defendants to construe the order in the way they had done, would be to defeat the object of the court in making the order.

Mr. FOLLETT, for the defendants, contended that the right construction had been put upon the order, which was to inspect the works, and that the order had been made by consent, and that no more extended order would have been consented to. The manufactory was at work in the usual course, and exactly as it would have been if the inspectors had not been there. The defendants had greatly improved the manufacture, but certain parts of the processes were known only to themselves, and they had made important discoveries in the manipulation of the materials, of which the plaintiffs wanted to get the benefit, and the effect of such an order as asked for would be to give them the advantage of the defendants' discoveries, even though their patent should be determined to be invalid. The inspection was consented to only as ancillary to an action-at-law, and to facilitate the trial of the plaintiffs' right, for which purpose the inspection had been sufficient. The plaintiffs, though they had undertaken to do so, had brought no action, and the defendants had brought a scire facias to repeal their patent, which they intended to try as soon as possible.

Lord LANGDALE said the order for inspection was made by consent, and he had no

power to make the order asked for. He had no inclination to grant an injunction, but had been desirous of aiding both parties to try the case fairly at law. He thought the construction of the order the right one, and that the inspectors having seen the defendants produce the same result as the plaintiffs by what they considered their protected process, and that it was done by means of certain powders which they were not permitted to test, a jury would probably infer that the processes were the same, or at any rate it would be incumbent on the defendants to show the difference.

His lordship therefore refused the motion.

NOTES AND NOTICES.

Mammoth Steam Engine. An enormous cy. linder of 144 inches diameter, for the great engine designed to drain the Haarlem Lake, has been cast at the foundry of Messrs. Harvey and Co. of Hayle; it is the largest cylinder ever cast entire for any purpose. A blast cylinder of 144 inches has, indeed been constructed at the same works, but this was cast in parts. The largest cylinder ever made for mining purposes was of the diameter of ninety inches and a fraction. It was boasted, a few days since, that the cylinders for her Majesty's steam frigate, Penelope, were, the largest ever The cast, being ninety-two inches in diameter. cylinders of the Penelope, however, are only two-fifths the size of that cast at Hayle, the piston of one containing 6647 square inches, that of the other 16,286; the operation was completely successful. than twenty five tons of iron were melted for the occasion, and the whole of that mass of liquid fire ran out into the mould in less than six minutes: not a single casualty occurred. The ironfounders of Hayle may now justly boast that they have executed by far the greatest work in their line which has ever been attempted.-Mining Journal.

More

Cheap Galvanic Battery.-A correspondent of the Glasgow Practical Mechanic states, in consequence of the expense, and for other reasons, he has modified the arrangements of De Moleyns, Grove, and Silliman, so as to do away with the diaphragms altogether, and makes the plumbago element the containing vessel for the nitric acid. He supposes this modification to possess another advantage in this, that it brings the elements into closer contact, and makes it equal, if not superior, to a platinised battery of the same surface. The cost of a battery of this description, he states to be as follows:-plumbago 2d., zink 14d., jar 14d.-in all 44d. With this battery a great variety of electro-magnetic experiments may be worked, and phenomena produced, as giving shocks with coals, deflagrating metals, &c. Important to Mechanics' Institutions.-An act was passed on the 28th ult., to exempt all scientific and literary societies from parochial and other rates, which act is appointed to come into operation on the 1st of October. It is required that societies, in order to avail themselves of this act, must cause three copies of their rules of management to be submitted to the barrister or persons appointed to certify the rules of friendly societies.

INTENDING PATENTEES may be supplied gratis with Instructions, by application (post-paid) to Messrs. Robertson and Co.